Stock 2.0l plenum and runners on 2270, It will flow enough air Options

[DNHunt]

I've almost finished tuning my engine with MS. It's one of Jake's 2270 kits and it has a fairly aggressive cam with lift just shy of .500" on the exhaust and intake with plenty of duration and overlap. The valves are 44 X 36 and there is some slight porting. At any rate it will pump a great deal more air than a stock engine.

The only mods I have made to my intake system are rebore of the throttle body to 50mm from the stock 45mm and a K&N air filter in the stock air box.

There has always been a question about the limits of the stock intake system on a modified engine. I think I can say I'm convinced that it will support my engine without trouble with the rebored throttle body.

The proof is in the logs I have been recording and which can be seen on the graph below. This represents acceleration through the first 3 gears with 3rd at WOT. The boxes at the lower left show RPM's at 6400, the manifold pressure is 94 kpa and the throttle position is 100% (WOT).

Atmospheric pressure that day was 97 kpa so the engine drops 3 kpa through the air filter. The purple line in the yellow circle tells the story. It stays at a consistent 94 kpa from the time I open the throttle after shifting into 3rd at ~ 4000 RPM until I shift into 4th at 6400 RPM. If the intake could not supply enough air that purple line would fall indicating the engine is trying to suck more air.

For anyone considering fuel injecting a larger than stock engine don't rule out the stock intake until you prove it will not work. Boring the throttle body is an easy thing for a machinist (cheap too) to do. The hardest part of the whole thing is making a new throttle plate to fit the bigger bore and that didn't take more than an afternoon.